Inductor having a magnetic casing formed by stacked stampings

ABSTRACT

An inductor comprises a central core 1 having bevelled upper and lower edges. The core is surrounded by a coil or winding 3, and the magnetic circuit is completed by complimentary half shells 5 and 6 that surround the coil and mate with the bevelled core edges but which are separated therefrom by compressible films 4. Flanged assembly brackets 7 and 8 complete the structure and may be inwardly pinched to compress the films and thereby adjust the inductance value to a desired level. The void spaces 9 and 10 at the top and bottom of the core help to channel the flux through the shells 5 and 6.

United States Patent 1 Hesset al.

in] 3,824,517 [45 July 16, 1974 1 INDUCTOR HAVING A MAGNETIC CASING FORMED BY STACKED STAMPINGS [75] Inventors: Jean-Marc Hess, Chamalieres;

Adolph Knop, Orcines, both of France [73] Assignee: Constructions Electrotechniques du Certre, Blahzat, France [22] Filed: Feb. 26, 1973 [21] Appl. No.: 335,849

[30] Foreign Application Priority Data Feb. 28, 1972 France 72.06669 Jan. 17, 1973 France 73.01545 [52] US. Cl 336/83, 336/178, 336/210,

' 336/212 [51] Int. Cl. H011 27/26 [58] Field of Search 336/210, 212, 234, 83, 336/178 [56] References Cited UNlTED STATES PATENTS 461,135 10/1891 Stanley, Jr. 336/212 X 1,974,588 9/1934 Snell 336/212 X 2,294,322 8/1942 Van Der Woude 3361234 X 2,827,615 3/1958 Henderson 336/212 X 2,907,966 10/1959 Dierstein ..336/212X 3,636,488 1/1972 Wiesner 336/212 X FOREIGN PATENTS OR APPLICATIONS 1,560,537 l/l968 France 336/212 1,563,242 11/1969 Germany 336/212 1,571,834 5/1969 France 336/234 187,368 1/1964 Sweden 336/212 602,290 1948 Great Britain.. 336/234 Primary Examiner-Thomas J. Kozma Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak [5 7] ABSTRACT An inductor comprises a central core 1 having bevelled upper and lower edges. The core is surrounded by a coil or winding 3, and the magnetic circuit is completed by complimentary half shells 5 and 6 that surround the coil and mate with the bevelled core edges but which are separated therefrom by compressible films 4. Flanged assembly brackets 7 and 8 complete the structure and may be inwardly pinched to compress the films and thereby adjust the inductance value to a desired level. The void spaces 9 and 10 at the top and bottom of the core help to channel the flux through the shells 5 and 6.

16 Claims, 11 Drawing Figures Pmmzuwu 61914 SHEET 1 [1F 3.

PAIENIEuJuL 1 6 1974 3,824,517 sum 2 or 3 PATENTEUJUU 61914 3.824.511

SHEET 3 [1F 3 INDUCTOR HAVING A MAGNETIC CASING FORMED BY STACKED STAMPINGS The present invention concerns an inductor comprising a winding enclosing a core surrounded by a magnetic casing formed by stampings.

Inductors of this type are already known, but none possesses the necessary technical qualities in return for a low cost price.

Although there are inductors, the manufacturing cost of which is reduced by the use of a casing formed of two half-shells joined together around the wound core, these half-shells which comprise an assembly of stampings of practically the same length as the core and were formed after stacking in order to adapt them to the shape of the core, tend to be the seat of Foucault currents.

These currents involving useless wastage of material by the provision of perforations in the stamping, may be partially eliminated or, alternatively, the stampings may be separated by a layer of varnish, since varnish has a low heat conductivity. However, in this case, the dissipation of the heat produced by losses due to Joule effect in the winding and to a lesser degree due to Foucault currents and hysteresis losses in the core, is made difficult.

Other inductors are known, formed by a winding mounted on the vertical portion of a stack of T-shaped stampings, the casing being formed by a stack of U- shaping of the U and T- shaped parts involves wastage of material in the stamping out of sheet metal, thus contributing to an increase in the price.

The principal object of the present invention is to provide an inductor formedby a winding mounted on a core and enclosed by a magnetic casing formed by the union of two half-shells disposed edgewise relatively to the core, each half-shell being formed by a stack of stampings located perpendicularly to the axis of the core, the said inductor being characterised in that the said stampings have aninner profile presenting at each end a portion resting over a certain length on an'end of the core, and an end portion separated therefrom, each pair of adjacent ends of the outer profiles of the halfshells being provided with an independent flange covering the corresponding end of the core and connecting the said adjacent ends together in such manner that there is always an empty space defined by each flange, the core and the end portions of the inner profiles of the edgewise stampings contained between the flange and the core.

Such an inductor, whether it is an induction coil or a transformer, has the advantage of being easily assembled, of reducing the Foucault currents in the casing and facilitating the dissipation of the heat emitted, by the inductor owing to the excellent conduction offered by the stampings of the casing located perpendicularly to the axis of the core. Moreover, the provision of the empty space between the base, the core and the portions of the inner profiles of the edgewise stampings contained between the flange and the core results in more efficient channelling of the magnetic flux near the end of the core than in previous inductors provided with an outer casing, whilst facilitating the assembly of the half-shells by means of two independentflanges.

Another object of the present invention is an inductor of the above type, the stampings of which, forming the half-shells, have an outer profile presenting at each end a projection on which the side edge of each flange rests, at least one of the flanges extending beyond the half-shells to serve as a mounting base. I

This construction thus facilitates the assembling of the half-shells, since it is only necessary to provide a suitable shape for two opposed edges of each flange cooperating with the end projections of the half-shells to connect these half-shells with each other. Moreover, each flange may act as a mounting base of the inductor on any desired device or support and mayalso serve as a support for any desired identifying marks, a need which is frequently imperative for using this type of electric component.

Another object of the present invention is also to reduce the cost of manufacture of the inductor by the practically complete elimination of wastage of metal resulting from the formation of the stampings, the stacks of which form the half-shells enclosing the core by the formation of stampings whose outer profile may be juxtaposed with the profile of its inner portion, the edges of the stampings between the ends of these profiles being formed of a straight portion acting as a support for a mounting base of the said inductor.

It is therefore only necessary to stamp out these parts from strips, the width of which corresponds to the distance of the edges formed by a straight portion in order to utilise all the strips without loss of material other than two small portions at the ends of the strip.

Another object of the present invention is an inductor of this type, each projection of which is formed by an acute angle, one side of which coincides with the straight edge joining the end of the outer profile with the end of the inner profile and the other side of which is equal and parallel to the portion of the inner profile between the core and the flange.

In this manner the dispersion of magnetic flux is minimised, and a convenient method of securing the flanges for keeping the half-shells pressed against the wound core -is obtained. It will also be noted that this core is almost completely contained within the two-half-shells and the small portions disposed on the axis of the core not enclosed by the casing, owing to the correspondence between the inner and outer profiles, are retracted relatively to the flanges. The contact of the assembly of this type of inductor with the device on which it may be used is therefore effected externally of the influence of the dispersion flux caused by the air gap or clearance, with the result that any risk of vibration of the support of the inductor is eliminated.

Inductors of this type may, under these conditions, be assembled and adjusted very easily, since it is onlynecessary to keep the flanges in contact with the straight portions of the half-shells joining the ends of the inner and outer profiles and to push back, in a single operation, the pre-formed longitudinal edges of the flanges to make them cover the angles provided on the outer profiles of the half-shells. In order to obtain any desired adjustment, it is only necessary to connect the inductor to the measuring devices, to provide between the end surfaces of the core and the half-shells a compressible material for adjusting the air gap and to press the halfshells, during the covering of the longitudinal edges of the flanges, against the angles provided on the ends of the half-shells until the measuring devices indicate the desired value of the inductor.

It is, only necessary to provide flanges the length of which is greater than that of the half-shells so that the stamping folded. over the shells holds the sides of the half-shells. In this manner the inductor is assembled and adjusted in a single operation.

The resultant excellent positioning makes it possible to avoid any gluingof the half-shells or any longitudinal soldering, whatever the method of constructing the core may be, whether it is formed by a stack of transverse or longitudinal stampings.

Another object of the present invention is to improve the magnetic flux circuit by selecting for supporting lengths, edgewise stampings on the ends of the core, a length substantially equal to the widthof these stampings in the median plane parallel to the two flanges.

However, despite this arrangement, it has been found that the magnetic circuit may be further improved in cases where the stampings are formed, in order to avoid any useless waste of material during manufacture so that the outer profiles of the stampings are capable of being superimposed on the inner profiles. In fact, in this case, the straight section offered to the flux is generally very narrow at the level of the supporting point near the winding and in the particular case in which the straight section is constant along the stampings on edge in the form of a square, this special shape imposed on the half-shells cannot correspond to the shape of the desired winding or even to the desired outer shape of the casing.

Another object of the present invention is to further improve the magnetic circuit in the case of half-shells,

the stampings of which have an inner profile capable of being superimposed on the outer profile along the" edges of the outer profiles by assembling flanges until the side edges of the flanges are beyond the straight section perpendicular to the profile of the stampings passing through the supporting point of the stamping on the core near the winding.

Hence, for a very slight increase in the width of each flange, the magnetic circuit is improved whilst the good condition of the assembly of half-shells is reinforced.

Finally, the increase in the width of the flanges is utilised, on the one hand, to avoid tearing of the lower flange originally provided to keep the outer stampings of the half-shells in contact and, on the other hand, to provide effective protection for the connecting wires of the inductor by means of the upper base.

In order that the invention may readily be carried into practice, a few embodiments will now be described in detail, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a cross section through an inductor. FIG. 2 is an elevational view of one end of the inductOl',

FIG. 3 is-a side view of the inductor,

FIG. 4 isa cross-section through an inductor having a core formed by transverse stampings,

FIG. 5 is a cross-section through an inductor having a core comprising longitudinal stampings,

FIGS. 6 8 show plan views of three types of stampings of the magnetic casing,

FIG. 9 shows a front schematic view of the inductor, the upper flange of which protects the ends of the inductor,

FIG. 10 is a schematic end view of the inductor shown in FIG. 9 and,

FIG. 11' is 'a schematic view .of a cross-section through the inductor with the upper part removed.

The inductor, shown in cross-section in FIG. 1, comprises a core 1 formed by a stack of stampings, the profile of which is preferably hexagonal and at least symmetrical relatively to the axis 2 in order to reduce wastage of material during the forming of the stampings from the strip of sheet metal. I

A winding 3 longitudinally encloses the core 1 and leaves free the end surfaces to which an elastic layer 4 is applied which may be, for example, a film of polyterephthalate or any other compressible material. The object of this layer is to create an air gap between the core and the magnetic casing composed of stampings 5 and 6 stacked one upon the other to form two halfshells enclosing the core 1 and its winding 3.

In the embodiment concerned, each stamping 5 or 6- has an outer profile 5a or 6a juxtaposable with its inner profile 5b or 6!). The outer profiles terminate in small straight portions forming with the straight sides 5c and 5d, or 60 and 6d, small projections in the form of acute angles.

The connection of the assembly of wound core and half-shells is effected by means of flanges 7 and 8, the

edges 7a, 7b, 8a, 8b of which cover the respective projections on the ends of the profiles 5a and 6a near the sides 5c and 6c and the profiles 5a and 6a near the sides 5d and 6d.

The empty portions 9 and 10 between the core 1, the stampings 5 and 6 and the flanges 7 and 8 correspond to asphere in which the magnetic field is negligible, owing to the shape of the stampings 5 and 6 resting on the surfacesof the core 1 which are inclined relatively to the axis 2.

The ends 11 and 12. (FIG. 3) may contain all-the components required for producing a predetermined electric unit. The end 12 is electrically connected to a connecting member 13 by the connections 14.

For assembling, it is only necessary to connect the inductor to the desired'measuring circuit by means of a connecting member 13 attached at 14 to the winding of the inductor, to push back the edges 7a and 7b (FIG.

1), as also 8a and 8b, against the stampings5 and 6 and thus to compress the film 4 between the core 1 and thehalf-shells to a certain degree until the measuring devices indicate the desired value of the inductor. With the use of a suitable 'tool it is possible at the same time to push back the edges of the flanges 7 and 8 located beyond the half-shells so that disconnections are obtained by means of the parts'7c, 7d, and 8d preventing any lateral displacement of the half-shells relatively to the flanges. v

Although the present invention has been described with reference to a preferred embodimentof the inductor, it is obvious that it is possible to depart more or less from the embodiments shown without departing from the scope of the present invention.

For example, FIGS. 4 and 5 show two identical inductors the stampings 5 and 6 of which form the magnetic casings and the flanges 7 and 8 have the same configuration, only the cores havingia different structure. In FIG. 4, the core is formed by transverse members l, whilst the core shown in FIG. 5 is formed of Iongitudunal stampings 15, shown, for the sake of clarity, as an end view and not in cross section.

In both cases these stampings may be formed practically without loss. The hexagons 1 may, in fact, be stamped out in rows perpendicular to the axis 2, for example, the hexagons of two consecutive rows being relatively displaced by one half-width. Since the stampings are rectangular, there is no need of displacement.

After the stampings 15 have been assembled, the ends which have to come into contact with the members 5 and 6 can be burred or provided with a film of polyterephthalate or any other compressible material, if it is desired to provide an air gap.

Similarly, the projection on the outer profile of the stampings 5 and 6 could have the most diverse shapes, whilst the profile of the winding could itself have a shape resembling a winding having a rectangular or triangular cross-section. By way of an example, FIGS. 6, 7 and 8 show three forms of the members 16, 17 and 18 having different profiles and identical projections. These members are stamped out without waste from strips 19, 20 and 21 of'suitable width. The last type 18 has the advantage of comprising a constant straight section.

The inductor shown in FIG. 9 again comprises a casing 31 a lower flange 32 preferably also serving for securing of the assembly and an upper flange 33,

The casing 31 is formed of two half-shells 34 and 35, (FIG. 10) assembled by the flanges 32 and 33. FIG. 11 shows how the flange 32 keeps the stamping such as 36 and 37 together. The flange 33 connecting the members in the same manner is not shown in FIG. 11.

This Figure shows the stampings 36 and 37, the stacks of which located parallel to the longitudinal axis 38, represent the respective half-shells 34 and 35. The axis of the winding 39 is the axis 40 and the core 41 is preferably formed by stampings parallel with the axes 38 and 40.

In order to improve the flow ofthe flux, the length L of the part of the member 36 resting on the core 41 is made substantially equal to the width L, of the member at the level of the median plane parallel to the flanges 32 and 33, i.e., extending through the axis 38. The effect of this is to provide the first improvement to the magnetic circuit. Furthermore, when the outer profiles 37a and inner profiles 37b of the edgewise stampings forming the half-shells are superposable, the width L of the members of the casing is generally relatively slight in the region of the winding adjacent to the end of the core 41, as stated above. This reduction in the cross-section of the magnetic flux at this point has been surmounted by laterally extending the flanges 32 and 33 until the edge thereof, such as 32a for example, is beyond the section perpendicular to the profiles 37a, 37b extending to the end of the part of the winding 39 located near the end of the core. The result of this is that the effective width of the half-shells at this point then passes from the width L to the width L thusimproving the flow of flux in the entire area between the surface .of the core where the stampings 36 and 37 are of a length L; substantially'equal to L and the section on the right of the edge 32a of the flanges.

Furthermore, since the flanges 32 and 33 are wider, an improved assembly of the half-shells is obtained. In fact, this increase is sufficient to keep the end members 42 and 43 compressed (FIG. 9) by slightly bringing together the edges 32a of the parts 32b and 32c of the flange located adjacent to the members 42 and 43 without having to break the metal at these points.

It is therefore possible, if desired, to increase the thickness of the flange thus contributing again to increase the strength of the assembly whilst improving the circuit of the flux, the width L (FIG. 11), being achieved.

It is also possible to make the upper flange 23 long enough to fold it along the ridges, 44 and 45 after stamping out before assembly a part of the flanks 33b and 330. Locking the edges at the level of the ridges 44 and 45 ensures the position of the faces of the members 42 and 43. In addition, the connections with the winding are efficiently protected in this manner by the faces 33a and 332 and by their edges 33b and 33c.

As an example of assembling, an inner insulating stamping is shown at 46 and at 47 (FIG. 10) a small insulating stamping is shown having two connecting plugs 48 and 49.

It is obvious that the plugs could pass directly through the face 33d by suitablev passages and that many other modifications of detail could be made to the described and illustrated inductor without departing from the scope of the present invention.

What we claim is:

1. An inductor formed by a winding mounted on a core and enclosed by a magnetic casing formed by the assembling of two half-shells disposed edgewise relatively to the core, each half-shell being formed by a stack of stampings located perpendicularly to the axis of the core, the said inductor being characterized in that the said stampings have an inner profile presenting at each end a portion resting over a certain length on one end of the core, an end portion separated therefrom and an outer profile presenting at each end a projecting shape, each side of each projecting shape forming an acute angle with the end of the outer profile, each pair of adjacent ends of the outer profiles of the half-shells being provided with an independent flange having a generally flat cross-section with its edges bent to form an acute angle therewith, said edges engaging the outer profile projections of said stampings, covering the corresponding end of the core and connecting together the said adjacent ends in such manner that there is an empty space,'continuous along the axis of the core, defined by each flange, the core and the end portions of the inner profiles of the edgewise stampings between the flange and the core.

2. An inductor as claimed in claim 1, wherein at least one of the said flanges extending beyond the half-shells to serve as a mounting base.

3. An inductor as claimed in claim 1, wherein the stampings of at least one half-shell simultaneously have an outer profile juxtaposable with the inner profile and a straight portion connecting the said profiles together and serving as a support for a mounting base of the said inductor.

4. An inductor as claimed in claim 1, wherein the lengths of the flanges are greater than the length of the half-shells and wherein the longitudinal edges of the portions not opposite the outer profile projections of the outer profiles are curved to serve as an abutment for the end stampings.

5. An inductor as claimed in claim 1, wherein the core is formed by the stacking of stampings in the form of a hexagon having an, axis of symmetry passing through two opposed apices, each of the apices being located between a flange and the ends of the inner profiles of the stampings located on either side of the core.

6. An inductor, as claimed in claim 1, wherein the core is formed of stampings in the form of rectangles 'of decreasing height and stacked so as to present a cross-section in the form of a hexagon, each of the ends of the centre member, of greater height, being located between a flange and the ends of the inner profiles of the stampings located on either side of the core.

7. An inductor, as claimed in claim 6, wherein the parts of the core without a winding opposite the stampings of the magnetic casing are burred to present a flattened surface.

8. An inductor, as claimed in claim 1, comprising, between the core and the portion of the inner profiles of the members forming the magnetic casing resting over a length of the core, a compressible material creating an air gap as a function of the pressure provided by each of the flanges laterally supported on the projections formed by the end of the outer profiles of the said members of the magnetic casing.

9. An inductor, as claimed in claim 3, wherein the straight portion of each stamping of the half-shells is constant.

10. An inductor, as claimed in claim 1, wherein the bearing length of the edgewise stampings on the ends of the core is substantially equal to the width of these stampings in the median plane of the inductor parallel to both flanges. I v

11. An inductor, as claimed in claim 1, wherein the inner profiles of the stampings of the half-shells may be superimposed on their outer profiles, also wherein the lateral edges of the flanges extend beyond the straight section of the stampings perpendicular to their profiles and substantially extending to the end of the winding adjacent to the end of the core.

12. An inductor, as claimed in claim 11, wherein the total width defined by the said straight section and comprising, on the one hand, the cross-section of the flange and, on the other hand, the cross-section of the stamping, is substantially equal to the bearing length of the stamping on the core.

13. An inductor, as claimed in claim 10, wherein a portion of the edge of the lower flange opposite the outer faces of the end stampings are bent parallel to the faces of the stamping for keeping the end stampings from moving along the axis of the core, limiting the the winding.

half-shells.

14. An inductor, as claimed in claim 10, wherein the upper flange is bent at both ends to form two faces protecting the ends of the said inductor, each face being also provided with two lateral edges protecting the connecting wires of the winding.

15. An inductor, as claimed in claim 14, wherein at least one of the said protecting faces is provided with at least one passage for establishing connections with 16. An inductor, as claimed in claim 15, wherein at least one of the said protecting faces supports an insulating plate to which the connecting plugs of the said winding are secured.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, h5 7 Dated July 16, 1974 Inventor(s) Jean-Marc Hess et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet, in item F75] "Certre, Blahzat,

' France" should read Centre, Blanzat, France Signed and Scaled this Fourth Day Of January 1977 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ofPalents and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 5, H Dated uly 1974 Inventor(s) Jean-Marc Hess et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet, in item F73] "Certre, Blahzat,

France" should read Centre, Blanzat, France Signed and Sealed this Fourth D3) Of January 1977 [SEAL] I Attest:

C. MARSHALL DANN Commissioner uj'latems and Trademarks RUTH C. MASON Attesting Officer 

1. An inductor formed by a winding mounted on a core and enclosed by a magnetic casing formed by the assembling of two half-shells disposed edgewise relatively to the core, each halfshell being formed by a stack of stampings located perpendicularly to the axis of the core, the said inductor being characterized in that the said stampings have an inner profile presenting at each end a portion resting over a certain length on one end of the core, an end portion separated therefrom and an outer profile presenting at each end a projecting shape, each side of each projecting shape forming an acute angle with the end of the outer profile, each pair of adjacent ends of the outer profiles of the half-shells being provided with an independent flange having a generally flat cross-section with its edges bent to form an acute angle therewith, said edges engaging the outer profile projections of said stampings, covering the corresponding end of the core and connecting together the said adjacent ends in such manner that there is an empty space, continuous along the axis of the core, defined by each flange, the core and the end portions of the inner profiles of the edgewise stampings between the flange and the core.
 2. An inductor as claimed in claim 1, wherein at least one of the said flanges extending beyond the half-shells to serve as a mounting base.
 3. An inductor as claimed in claim 1, wherein the stampings of at least one half-shell simultaneously have an outer profile juxtaposable with the inner profile and a straight portion connecting the said profiles together and serving as a support for a mounting base of the said inductor.
 4. An inductor as claimed in claim 1, wherein the lengths of the flanges are greater than the length of the half-shells and wherein the longitudinal edges of the portions not opposite the outer profile projections of the outer profiles are curved to serve as an abutment for the end stampings.
 5. An inductor as claimed in claim 1, wherein the core is formed by the stacking of stampings in the form of a hexagon having an axis of symmetry passing through two opposed apices, each of the apices being located between a flange and the ends of the inner profiles of the stampings located on either side of the core.
 6. An inductor, as claimed in claim 1, wherein the core is formed of stampings in the form of rectangles of decreasing height and stacked so as to present a cross-section in the form of a hexagon, each of the ends of the centre member, of greater height, being located between a flange and the ends of the inner profiles of the stampings located on either side of the core.
 7. An inductor, as claimed in claim 6, wherein the parts of the core without a winding opposite the stampings of the magnetic casing are burred to present a flattened surface.
 8. An inductor, as claimed in claim 1, comprising, between the core and the portion of the inner profiles of the members forming the magnetic casing resting over a length of the core, a compressible material creating an air gap as a function of the pressure provided by each of the flanges laterally supported on the projections formed by the end of the outer profiles of the said members of the magnetic casing.
 9. An inductor, as claimed in claim 3, wherein the straight portion of each stamping of the half-shells is constant.
 10. An inductor, as claimed in claim 1, wherein the bearing length of the edgewise stampings on the ends of the core is substantially equal to the width of these stampings in the median plane of the inductor parallel to both flanges.
 11. An inductor, as claimed in claim 1, wherein the inner profiles of the stampings of the half-shells may be superimposed on their outer profiles, also wherein the lateral edges of the flanges extend beyond the straight section of the stampings perpendicular to their profiles and substantially extending to the end of the winding adjacent to the end of the core.
 12. An inductor, as claimed in claim 11, wherein the total width defined by the said straight section and comprising, on the one hand, the cross-section of the flange and, on the other hand, the cross-section of the stamping, is substantially equal to the bearing length of the stamping on the core.
 13. An inductor, as claimed in claim 10, wherein a portion of the edge of the lower flange opposite the outer faces of the end stampings are bent parallel to the faces of the stamping for keeping the end stampings from moving along the axis of the core, limiting the half-shells.
 14. An inductor, as claimed in claim 10, wherein the upper flange is bent at both ends to form two faces protecting the ends of the said inductor, each face being also provided with two lateral edges protecting the connecting wires of the winding.
 15. An inductor, as claimed in claim 14, wherein at least one of the said protecting faces is provided with at least one passage for establishing connections with the winding.
 16. An inductor, as claimed in claim 15, wherein at least one of the said protecting faces supports an insulating plate to which the connecting plugs of the said winding are secured. 